ABSTRACT
Colon cancer is a prevalent human malignancy. HER2/neu is an important oncogene in breast cancer, but its prevalence and significance in colon cancer have been poorly documented. The aim of this study is to determine the rate and pattern of HER2/neu expression in colon carcinoma by immunohistochemistry [IHC]. Sixty-nine archival, paraffin wax embedded colon carcinoma specimens were chosen. IHC for HER2/neu was performed. Clinicopathologic data and IHC results were analysed. Most of the carcinoma cases were well differentiated and located in the left side. There was positive HER2/neu staining in a high percent of cases [41 Cases, 59.4 %] with both cytoplasmic [27 cases, 65.9%] and membranous-cytoplasmic [14 cases, 34.1%] staining. There was positive HER2 staining in 66.7% of stage B, in 58.6% of stage C and 28.6% of stage D cases. In higher stages, the rate of positive staining was decreased but there was higher rate of strong membranous staining. There was positive HER2 staining in 28 [66.7%] of well differentiated and in five [35.7%] of moderately differentiated cases. In addition, in higher grades, the rate of HER2/neu staining was decreased [p=0.04] and there was more membranous staining. There was no correlation between HER2/neu expression and age, sex, site and type of tumor. The rate of HER2/neu expression in colon carcinoma is high. Because of more prominent membranous staining in higher stages and grades, Herceptin therapy could be helpful in patients with lymph node or distant metastases